The tragedy occurred at a satsang, a Hindu religious gathering, in Hathras district, Uttar Pradesh state.
Authorities are still working to identify the victims, many of whom are women and some children.
A spokesperson for a senior police officer in Uttar Pradesh told the BBC that it would "take hours to finalize the count," but confirmed that at least 100 people had died.
An eyewitness, who preferred not to be named, told the BBC that everything was proceeding smoothly until suddenly, screams were heard and people began falling over each other.
"Many people were crushed, and there wasn't much I could do. I feel fortunate to have survived."
A woman named Shakuntala told the Press Trust of India news agency that after the sermon ended, everyone began running out.
People fell into a roadside drain, stacking on top of each other and getting crushed to death.
Umesh Kumar Tripathi, the chief medical officer from the nearby district of Etah, informed reporters that the "stampede" had resulted in the deaths of at least three children.
Disturbing images from the scene are being shared on the internet. Several videos depicted injured individuals being transported to hospitals in pickup trucks, auto rickshaws, and even motorcycles.
A video viewed by the BBC depicted multiple bodies left at the entrance of a nearby hospital while relatives cried out for assistance.
In another video, a relative remarked, "Such a big accident has occurred, but there isn't a single senior officer here. Where is the administration?"
Mr. Kumar mentioned that the venue was overcrowded and stated that a committee of senior officials had been established to investigate the incident.
He stated that the administration's main priority is to offer assistance to the injured and the families of those who died.
A video released by the news agency PTI depicted injured individuals being transported to a hospital for medical treatment.
Official Satya Prakash in the nearby district of Etah stated that the post-mortem procedure is currently ongoing and the matter is under investigation.
In Hathras, the cries of distressed family members echo through the local hospital.
Many people are searching for their loved ones, and there are many unclaimed bodies.
Accidents frequently occur at religious events in India, where large crowds gather in confined spaces with minimal adherence to safety measures.
In 2018, approximately 60 people died when a train collided with a crowd watching celebrations for Dusshera, a Hindu festival.
In 2013, a stampede at a Hindu festival in the central state of Madhya Pradesh resulted in the deaths of 115 people.
SOURCE: BBC